(a) Field of the Invention
The present invention relates to a catalyst, and more particularly, to a transition metal-based structurally ordered mesoporous catalyst.
(b) Description of the Related Art
Fuel cells are expected to be one of the most promising power sources for application to portable equipment, small power generation, and transportation because of their high energy conversion efficiency and environment-friendly characteristics such as not emitting pollution.
As a catalyst that stimulates a core reaction in driving these fuel cells, one in which platinum nanoparticles are dispersed in a carbon carrier has been generally used. However, various problems of the platinum-based catalyst, such as deterioration in performance due to agglomeration of the nanoparticles upon long-term use, and limited platinum reserves, are becoming obstacles to the distribution of fuel cells.
Therefore, there is a growing interest in the development of low-cost and high-performance non-platinum-based catalysts that are capable of overcoming drawbacks of the platinum catalysts.
Since it was reported about 50 years ago that molecules having a cobalt-nitrogen coordination structure have activity on the fuel cell catalytic reaction, studies on the non-platinum-based catalysts have been continuously conducted. The non-platinum-based fuel cell catalyst has rich reserves of transition metals (mainly iron or cobalt), nitrogen, and carbon as main components. The non-platinum-based fuel cell catalyst is synthesized by mixing precursors containing those components, followed by high-temperature thermal treatment.
Although performance improvement of the non-platinum-based catalysts has occurred through optimization of the above-mentioned synthetic method over the past few years, non-platinum-based catalysts still remain at a lower level as compared with platinum-based catalysts.
In the process of preparing these transition metal-based catalysts, methods of using carriers such as carbon black and the like have been widely used in order to overcome a low surface area.
Although the use of the carrier such as carbon black is effective in increasing the active surface area, carbon black without activity accounts for most of the mass of the carrier itself, causing deterioration in mass activity thereof. Moreover, micropores present in the carbon black are disadvantageous in the mass transfer of reactants and products.
Further, since it has been known that the performance is more improved when thermal treatment is conducted in the condition of a reactive gas such as ammonia than in the condition of an inactive gas such as argon or nitrogen, the synthesis conditions may be somewhat severe.